GEONS Geomagnetic Event Observation Network By Students

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GEONSGeomagnetic Event Observation Network By
Students
Calculating B, and K using ASCII Data By James
Bridegum, Emilia Groso, Lindsey Peterson, Merrill
Asp, and Lisa Beck Carson High School, Carson
City, NV Astrophysics Students
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Objectives

• This presentation will show how to use THEMIS
  data to calculate the K index using archived
  ASCII data for Petersberg, Alaska.
• Geographic Latitude, Longitude, and Altitude
• 56.83 N, 133.16 W, Alt n/a
• Calculate local B-values for the above mentioned
  location.
• The following locations and months are shown in
  this presentation as working examples.
• THEMIS Magnetometer Data for Petersburg, Alaska.
• June 1st, 2008 through September 30th, 2008.

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Petersburg, Alaska
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Magnetic Flux Density (B)

• The measure of the strength of a magnetic field.
• The scientific unit is Teslas (T)
• Calculated by
• Where
• X The strength of the magnetic field in the
  direction of the north pole
• Y The strength of the magnetic field in the
  eastward direction
• Z The strength of the magnetic field pointing
  down
• This is demonstrated in the graph on the
  following slide

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Magnetic Flux Density (continued)

• For more information, see Dr. Peticolas
  presentation at http//ds9.ssl.berkeley.edu/themi
  s/presentations/peticolas_mag_science06/peticolas_
  mag_science_files/frame.html

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Coronal Mass Ejections

• Plasma clouds consisting of protons and electrons
  that are released from the sun.
• These clouds of charged particle cause
  disruptions in the Earths magnetic field.
• We are trying to chart these disturbances.

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Definitions

• The K-index is a code that is related to the
  maximum fluctuations of horizontal components
  observed on a magnetometer relative to a quiet
  day, during a three-hour interval.
• K-index is determined after the end of prescribed
  three hourly intervals (0000-0300, 0300-0600,
  ..., 2100-2400) in Universal Time (UT)
• The relationship between K, and Kp
• The official planetary Kp index is derived by
  calculating a weighted average of K-indices from
  a network of geomagnetic observatories. For more
  information click on the link K-index
• The table below shows the relation of K and DB

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Observations and Limitations

• Space weather operations use near real-time
  estimates of the Kp index which are derived by
  the U.S. Air Force 55th Space Weather Squadron.
• The Kp index is derived using data from
  ground-based magnetometers at Meanook, Canada
  Sitka, Alaska Glenlea, Canada Saint Johns,
  Canada Ottawa, Canada Newport, Washington
  Fredericksburg, Virginia Boulder, Colorado and
  Fresno, California. (http//www.sec.noaa.gov/rt_pl
  ots/kp_3d.html)
• These estimated of Kp are based on a network of
  observatories reporting in near real-time.
• Due to real-time requirements it is possible that
  a local magnetometer, i.e. Petersburg, AK may
  detect a highly localized disturbance.
• The highly localized disturbance will affect the
  region, but the severity of the disturbance is
  underestimated on a planetary scale.
• The NOAA scale describes effects for various
  levels of activity, but with regards to
  geomagnetic activity, it needs to be kept in mind
  that there can be differences in the responses of
  local K-values that are a function of the
  location of the user.
• Therefore, the Kp values may be incomplete due to
  local real-time data not being reported.

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Using ASCII Data

• Tips on using MS Excel
• ASCII Data is in UT time
• 0001 hrs to 2400 hrs
• Two (2) data points per second
• 1-day 172, 800 data points
• Excel has column restriction to about 65,000
• Making 3-columns in order to divide up the data
  is convenient
• Column 1 0- 32,400 data points (Time Period 1)
• Column 2 32,400- 64,800 data points (Time Period
  2)
• Column 3 64,800-86,400 data points (Time Period
  3)
• In each of these divisions, there will be four
  more columns
• Column 1 Shows the time (in seconds)
• Column 2 Shows fluctuations in the x-axis
• Column 3 Shows the fluctuations in the y-axis
• Column 4 Shows the fluctuations in the z-axix
• Be patient for copy-paste. It takes about 20-30
  seconds using a 1.66 GHz dual core processor.
• Be familiar with the Text to Column feature in
  the Data section of Excel
• A template had been previously made

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Example of Partial Template

• This only shows part of the time. The actual
  template will be much longer.

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Using ASCII Data

• Calculating maximum fluctuations
• In the x-axis column, determine Dx xmax xmin
• To determine K-value, compare Dx to the following
  chart values
• Researchers must be cautious of magnetic field
  component values (x, y, or z) values that are
  erroneous, i.e. too high, too low, or negative.
• Spectrograph plots are an invaluable tool to help
  differentiate between true solar storminess and
  human caused effects.
• If more than a single data point is affected, the
  corresponding 3-hour period should be deleted.
• Consequently, this will affect the calculation of
  B for the day. (Activity 20)

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• OUR DATA

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Data for June
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Data for July
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Data for August
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Data for September
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Statistical Analysis

• Normal Day
• A normal day is when the k-max is at the average
  for the month in the particular area.
• Petersburg, AK Kmax 5.10 /- 1.94, B
  54,419.08 nT /- 14.4 nT
• Active Day would appear to be Kmax
• An active day is when k-max is significantly
  higher than the locations average.
• The B-field appears to be holding at a constant
  strength.

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SpectrometersOn a Normal Day

• This shows the Spectrometer for August 14, 2008.
  
• On this day, we had a k value of 5, but the
  rectangular red bar, representing the highest k
  value, is probably due to human activity because
  of its unnatural regularity. However, the blue
  and yellow speckled areas are typical in most
  spectrometers from Petersburg.

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SpectrometersOn a High Activity Day

• This shows the Spectrometer for July 14, 2008.
• On this day, we had a k value of 9. It is
  obvious that this magnetic disturbance is due to
  magnetic storms because of the randomness in the
  spectrometer indicative of a natural event.

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K-Index Observations

• The k values for the planetary data are much
  lower than the data we collected for Petersburg,
  Alaska.
• This difference is due to the fact that
  Petersburg is closer to the real South Pole, so
  it receives more noticeable magnetic radiation.
• Although Petersburg receives more radiation than
  other locations, spikes in our data generally
  match spikes in the planetary data.

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Discussion

• Our data may be inaccurate because it appears as
  though there are several cases of human errors on
  the spectrometer graphs.
• Although our data is abnormally high, in an ideal
  circumstance the data for this location would
  still be higher compared to the planetary data.

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• The End